1. Field of the Invention
This invention in general relates to refrigeration circuits and a method of operation thereof. More particularly, this invention relates to refrigeration circuits, components, and subassemblies and methods of operating same wherein a condenser designed to operate as a portion of a high efficiency refrigeration circuit is paired with an evaporator designed to operate as a portion of a lower efficiency refrigeration circuit.
2. Prior Art
In a typical residential air conditioning application, a condenser is mounted in heat exchange relation with ambient air and an evaporator is mounted in heat exchange relation with the air of the enclosure to be conditioned. A compressor and an expansion device are joined with the condenser and evaporator to form a refrigeration circuit such that heat energy may be transferred between the enclosure air and ambient air.
As the cost of energy to operate an air conditioning system has increased, the manufacturers of air conditioning equipment have attempted to produce more energy efficient equipment. This change in energy efficient equipment has resulted in certain operational characteristic changes between earlier produced equipment and newer higher efficiency equipment.
One of the ways of achieving higher efficiency in an air conditioning system is to decrease the head pressure and consequently the condensing pressure.
In a typical residential air conditioning installation, the components of the refrigeration system perform for their useful life and then need to be replaced. Other components, often the indoor heat exchanger, may have a longer useful life and may continue to perform satisfactorily although the other components need to be replaced. This partial replacement may result in the compressor and condenser being replaced and the evaporator remaining from the original system.
The energy conscious consumer often desires to replace a portion of a system with newer higher efficiency equipment. The utilization of this higher efficiency equipment, however, presents a problem when it is combined with the evaporator from a refrigeration system having capillary tubes as expansion devices. The mating of refrigeration circuit components being designed to operate at different head pressures may result in a decreased capacity of the system, lowering the overall efficiency of the system and/or other operational problems. The severity of these problems depend upon various factors including the expansion device associated with the indoor heat exchanger and the sizing of interconnecting piping. Oftentimes an expansion device of a residential size evaporator comprises a series of fixed diameter capillary tubes.
Capillary tubes which are often used as the expansion devices in a residential size evaporator act to reduce the pressure of refrigerant flowing therethrough. These capillary tubes are sized to allow a predetermined mass flow rate at a given temperature and head pressure. If the head pressure is reduced the mass flow rate through the capillary tube may also be reduced. However, should the temperature of the refrigerant flowing through the capillary tube be reduced, the mass flow rate may increase since the viscosity of liquid refrigerant decreases as it is further subcooled.
The present refrigeration system and components are designed to provide an efficient refrigeration circuit having a replacement component designed to operate at a lower head pressure than the existing component to which it is to be matched.
Prior art devices incorporating subcoolers and intermediary heat exchangers are known in the art. The present invention utilizes an intermediate heat exchanger as a flash subcooler such that a portion of the liquid refrigerant circulating from the condenser to the evaporator is diverted to the intermediate heat exchanger wherein it is flashed to the compressor suction pressure. As the refrigerant changes state from a liquid to a gas it absorbs heat energy from the refrigerant flowing from the condenser to the evaporator subcooling same. Hence, the flow rate of refrigerant flowing through the condenser is different from the flow rate through the evaporator. However, the diverted portion of the refrigerant is not wasted since the heat energy that may have been absorbed upon the flashing of that refrigerant in the evaporator is used to further subcool the refrigerant entering the evaporator.